docs: def bind_env(self, *input_):
          """Binds a Vyper key to a ENV variable.
          ENV variables are case sensitive.
          If only a key is provided, it will use the env key matching the key,
          uppercased.
          `env_prefix` will be used when set when env name is not provided.
          """
          if len(input_) == 0:
              return "bind_env missing key to bind to"
  
          key = input_[0].lower()
  
          if len(input_) == 1:
              env_key = self._merge_with_env_prefix(key)
          else:
              env_key = input_[1]
  
          self._env[key] = env_key
  
          if self._key_delimiter in key:
              parts = input_[0].split(self._key_delimiter)
              env_info = {
                  "path": parts[1:-1],
                  "final_key": parts[-1],
                  "env_key": env_key
              }
  
              if self._env.get(parts[0]) is None:
                  self._env[parts[0]] = [env_info]
              else:
                  self._env[parts[0]].append(env_info)
  
          return None